Jay Cost of the Weekly Standard digs through the history books to document scandals comparable to the current controversy involving Democratic presidential front-runner Hillary Clinton.

Hillary Clinton is a scandalous candidate for president of the United States. Most people acknowledge this, at least judging by her plummeting poll numbers. A raft of stories gives the distinct impression that she and her husband have been running an elaborate pay-to-play operation. Donations to the Clinton Foundation may have produced favorable State Department policies dealing with Russia-owned U.S. uranium deposits, Haitian relief efforts, and foreign banking interests. Her use of a personal email server while at the State Department, moreover, strongly suggests she has something to hide.

Yet she is still on track to win the Democratic nomination next year. That would be a unique achievement, twice over. She would be the first woman to win a major party nomination—and no major party nominee has ever misused his public authority more egregiously than she seems to have. …

… The historical record is littered with dubious doings by eventual nominees. John Jacob Astor loaned James Monroe $5,000 during the War of 1812. As president, Monroe rescinded an order prohibiting foreigners from engaging in the fur trade, which helped Astor enormously. Andrew Jackson tipped off his friends to the invasion of Florida, signaling a potential investment opportunity. Henry Clay, Daniel Webster, and a slew of other politicians received money from the Second Bank in the 1820s. James Garfield was implicated in the Crédit Mobilier scandal. William McKinley and Benjamin Harrison were close to the Gilded Age’s worst political bosses. Alton B. Parker, Democratic nominee in 1904, was close to Tammany Hall. Woodrow Wilson allied with the New Jersey Democratic machine to win the governorship in 1910. Harry Truman was part of the Pendergast machine as a judge in Kansas City.

As in the Clinton scandals, it is tough to pin anything on any of these candidates definitively. That is typical of quid pro quo arrangements. The politician can always respond that the quo had nothing to do with the quid—that he acted as he did because of the merits of the case. Unless the FBI sets up an elaborate Abscam-style sting—in which the feds actually catch a politician on the record admitting he will change policies because of the payments being offered—it is tough to demonstrate guilt beyond a shadow of a doubt. Even then, pols can slip loose. John Murtha was caught on tape in Abscam, and his seemingly ambiguous answers allowed him to get off scot-free.

But citizens need not be bound by the same constraints as jurors. The evidentiary standard in a criminal case is so high because the penalty is imprisonment. Here, the “penalty” is a denial of higher office, so our standards can adjust accordingly. And it is a fair bet that while some of the aforementioned candidates were innocent, just as many were guilty.